CTD / CTDr

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Function Block A function block groups an algorithm and a set of private data. It has inputs and outputs. - Down counter.

Inputs

Input	Data Type	Description
CD	BOOL	Enable Enable signal for the drive, Hardware-Enable with 24V signal to X8, Software-Enable command by setup Software, fieldbus or permanently set. Both are required for enabling the drive. counting Internal count pulses, 1 pulse = 1/2^20turn.. Counter is decreased on each call when CD is TRUE.
LOAD	BOOL	Re-load command. Counter is set to PV when called with LOAD to TRUE.
PV	DINT	Programmed The act of performing a sequence of instructions or commands. maximum value.

Input

Data Type

Range

Unit

Default

Description

BOOL

Enable Enable signal for the drive, Hardware-Enable with 24V signal to X8, Software-Enable command by setup Software, fieldbus or permanently set. Both are required for enabling the drive. counting Internal count pulses, 1 pulse = 1/2^20turn..

Counter is decreased on each call when CD is TRUE.

LOAD

BOOL

Re-load command.

Counter is set to PV when called with LOAD to TRUE.

DINT

Programmed The act of performing a sequence of instructions or commands. maximum value.

Outputs

Output	Data Type	Range	Unit	Description
CV	DINT			Current value of the counter.
Q	BOOL			TRUE when counter is empty (i.e., when CV = 0).

Remarks

The counter is empty (CV = 0) when the application starts.
The counter does not include a pulse When the step gets activated, the action is activated for a single execution, and possibly once again when the step is deactivated. detection for CD input.
Use the f_trig or r_trig function A function calculates a result according to the current value of its inputs. A function has no internal data and is not linked to declared instances. blocks for counting pulses of CD input signal.
CTDr, CTUr, and CTUDr function blocks operate exactly as other counters.
- Exception: All Boolean inputs (CU, CD, RESET New start of the microprocessor., LOAD) have an implicit rising edge The transition of a digital signal from low to high. AKA: positive edge. detection included.

FBD Language Example

FFLD Language Example

The CD is the input rung.
- The output rung is the Q output.

IL Language Example

(* MyCounter is a declared instance of CTD function block. *)
Op1: CAL    MyCounter (CD, LOAD, PV)
FFLD     MyCounter.Q
ST     Q
FFLD     MyCounter.CV
ST     CV

ST Language Example

(* MyCounter is a declared instance of CTD function block. *)
MyCounter (CD, LOAD, PV);
Q := MyCounter.Q;
CV := MyCounter.CV;